The Cd2 and Zn2 van der Waals dimers revisited.: Correction for some molecular potential parameters

The excitation spectrum of Cd-2 van der Waals complexes produced in a free-jet supersonic expansion beam was studied using Ar as carrier gas and a pulsed dye-laser as light source. A well resolved structure of vibrational bands arising from transitions between X0(g)(+)((1)Sigma(g)(+)) and 0(u)(+)((3)Pi(u)) states were observed. Owing to the properties of the molecular beam we were able to obtain spectra with different progressions originating from higher (v" greater than or equal to 1) vibrational levels of the ground state. The 'hot band' frequencies made possible-for the first time-a direct determination of the ground state parameters of the molecule. We verified our earlier results of Cd-2 molecular spectra that were recently questioned by Helmi et al, [1]. We have also critically revised the previously reported, estimated bond-lengths of Cd-2 and Zn-2, demonstrating an excellent experiment-theory agreement of results of Refs. [2] and [3] and Refs, [4] and [5], respectively. (C) 1999 Elsevier Science B.V. All rights reserved.